1. Field of the Invention
The invention relates generally to code readers and particularly to readers which sense optically discernible symbol combinations or codes, such as bar codes and two-dimensional codes.
2. Discussion of the Related Art
A variety of types of illuminators and corresponding photosensors can be found in conventional code readers. Some read 1-D or 2-D codes through use of a phototransistor to sense reflections of laser diode light as it is scanned across a target code. Others employ 1-D and 2-D photodetector arrays to sense reflections from flash type illuminators or LED (light emitting diode) array.
Such varieties exist because not all types of illuminator and photosensor combinations perform the same. For example, some combinations: 1) exhibit reading ability over longer distances; 2) more easily recognize damaged codes; 3) read only 1-D type codes; 4) consume relatively more power; 5) require a greater footprint; 6) also capture non-code images; and 7) cost relatively less than other types of combinations.
Because of such variations in performance, to choose an appropriate type of code reader (i.e., to choose an appropriate illuminator and photosensor combination), the requirements of a given application must be examined. Requirements such as short range, portability, 1-D code reading only and low cost might result, for example, in the selection of a CCD type reader employing a photodiode array as the illuminator. Similarly, by also requiring long range performance might result in the selection of a scanning laser diode configuration. Therefore, for optimal performance, a user must purchase a conventional code reader which economically and reliably meets the requirements of the task at hand.
After appropriately selecting and purchasing a given code reader, however, many factors arise which cause the user to become dissatisfied with the reader. Such factors include, for example, changes in the requirements of the task at hand, changes in characteristics of current code reader types and developments of new types of code readers with entirely different operating characteristics. As a result, the user may be forced to purchase another code reader.
Moreover, in many circumstances, a single code reader cannot satisfactorily meet all of the requirements of the task at hand. In such situations, the best conventional code reader may only perform with marginal reading success, or only read certain types of codes. If multiple code reader types are not employed in such circumstances, the user must accept such undesirable limitations in performance. Further, when a code reader exhibits marginal success, users are much more likely to engage in a series of failed read attempts, wasting both energy (a significant factor in portable configurations) and user efficiency.
Thus, there is a need for a code reader which is capable of solving all of the foregoing problems. In particular, it is an object of the present invention to provide a code reader which exhibits or can be adapted to exhibit the characteristics of the various types of conventional code readers.